Physics 160 Biomechanics

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                                          Physics 160 Biomechanics
                                           Test #3 March 10, 2009
Instructor: Dr. Julie A lexander
Time: 50 minutes                                   Name _____________________________

1)   Which plane is perpendicular to the longitudinal axis?
     a) Frontal
     b) Sagittal
     c) Transverse
     d) Oblique
     e) Vertical

2)   A runner ran the marathon (approximately 42.0 km) in 2 hours and 57 min. what is the average speed
     of the runner in m/s?
     a) 124 m/s
     b) 14.2 m/s
     c) 7.65 m/s
     d) 3.95 m/s

3)   An angle formed between a segment and a horizontal reference line would be an examp le of
     a) An absolute angle
     b) A relative angle
     c) A double-jointed angle
     d) A goniometric angle
     e) A radial angle

4)   For a rotating object, the acceleration directed toward the center of rotation is called
     a) Tangential acceleration
     b) Rotary accelerat ion
     c) Centrifugal acceleration
     d) Linear acceleration
     e) Radial acceleration

5)   Mike runs in lane one around a curve, wh ile Maurice runs in lane eight around a curve. The radius of
     lane eight is twice as big as the radius of lane one. If M ike has to run 50 m to get fully around th e
     curve in lane one, how far does Maurice have to run to get fully around the curve in lane eight?

6)   Which of the follo wing is a correct unit of pressure?
     a) newton
     b) kg/cm2
     c) N/cm2
     d) Slugs

7)   Which of the follo wing types of force exerts a squeezing effect on the body ?
     a) Shear
     b) Co mpression
     c) Tension
     d) All of the choices are correct

8)   Which of the follo wing is/are scalar quantities?
     a) Force
     b) Mass
     c) Velocity
     d) All of the above are scalar quantities
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9)   Inertia is
     a) Something that causes or tends to cause a change in the motion of an object or body
     b) The space a body occupies
     c) A body’s resistance to having its state of mot ion changed
     d) The amount of matter an object contains
     e) The effect of a force

10) The force that acts perpendicular to an object in contact with a surface is called
    a) A shear force
    b) A normal force
    c) An internal force
    d) A collinear fo rce
    e) A resolved force

11) How does mass differ fro m weight?
    a) Mass is a force and weight is the quantity of matter in a body
    b) Weight is a force and mass is the quantity of matter in a body
    c) Mass refers to density and weight refers to volu me
    d) Weight refers to density and mass refers to volume
    e) Mass and weight are the same

12) What determines the time a horizontally projected object remains in the air?
    a) Weight
    b) Mass
    c) Projection height
    d) All of the choices are correct

13) Which of the follo wing would be typical for vert ical ground reaction force (GRF) during running?
    a) GRF=body weight
    b) GRF=2 X body weight
    c) GRF=1/ 2 body weight
    d) None of the choices are correct

14) When you sit on a chair, the resultant force on you is
    a) Up
    b) Down
    c) Zero
    d) Depends on your weight

15) Action-reaction forces
    a) Always act on the same object
    b) Somet imes act on the same object
    c) May be at right angles
    d) Always act on different objects

16) A stone is thrown straight up. At the top of its path, the net force acting on it is
    a) Instantaneously equal to zero
    b) Equal to its weight
    c) Greater than zero, but less than its weight
    d) Greater than its weight
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17) A 10 kg bo x sitting on a horizontal surface is pulled by a 5.0 N force. A 3.0 N friction fo rce retards the
    motion. What is the accelerat ion of the object?
    a) 0.30 m/s 2
    b) 5.0 m/s 2
    c) 0.50 m/s 2
    d) 0.20 m/s 2

18) What type of energy is strain energy?
    a) Potential
    b) Kinetic
    c) Caloric
    d) Entropic

19) The product of a body’s mass and its linear velocity defines
    a) Linear mo mentu m
    b) Linear impulse
    c) Linear torque
    d) Linear inertia
    e) Mechanical work

20) Energy of mot ion is also called
    a) Potential energy
    b) Kinetic energy
    c) Strain energy
    d) Elastic energy

21) If a   25 kg student climbs two steps of 20 cm each, the work performed is
    a)     10 J
    b)     100 J
    c)     1000 J
    d)     10,000 J
    e)     Need more informat ion to calculate

22) Two horizontal forces act on a 5.0 kg mass. One force has a magnitude of 8.0 N and is directed due
    north. The second force toward the east has a magnitude of 6.0 N. What is the acceleration of the
    mass?
    a) 2.0 m/s 2 at 53o E o f N
    b) 1.6 m/s 2 37o N of E
    c) 2.0 m/s 2 at 53o N of E
    d) 1.2 m/s 2 due east

23) Bill bench presses a 95 kg barbell a distance of 0.8 m in 1.1s. What is the power of this lift?




24) A 90 kg running back is div ing towards the end zone with a horizontal velocity of 5 m/s. He is hit in
    midair by a 100 kg linebacker who is diving in the opposite direction with a horizontal velocity of 4
    m/s. what is their co mb ined velocity after the collision?
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Answers:

   1)    C
   2)    D
   3)    A
   4)    E
   5)    100 m
   6)    C
   7)    B
   8)    B
   9)    C
   10)   B
   11)   B
   12)   C
   13)   B
   14)   C
   15)   D
   16)   B
   17)   D
   18)   A
   19)   A
   20)   B
   21)   B
   22)   C
   23)   677 W
   24)   0.26 m/s